A group of more than 100 young people were causing trouble for up to five hours before the incident in which a young man was severely injured in a collision with a garda car in north inner Dublin, local people said yesterday.

A group of more than 100 young people were causing trouble for up to five hours before the incident in which a young man was severely injured in a collision with a garda car in north inner Dublin, local people said yesterday.

The man who was injured was named locally as Evan Molloy, in his 20s. He was on a motorcycle which was involved in a collision with a squad car on Buckingham Street a few hundred metres from the scene of the Christmas night disturbances in Seville Place in north inner Dublin. He was transferred from the Mater to Beaumont Hospital yesterday morning for treatment for serious head injuries.

Local people said the injured man's brother, Gareth, was shot dead by gardai during the attempted robbery of a security van in Lucan, Co Dublin in May 2009.

The collision, which happened around 5am, is being investigation by the Garda Siochana Ombudsman Commission (GSOC), as is normal in incidents involving traffic incidents and gardai.

Local people were yesterday critical of the gardai response to disturbances, with one local man saying he called gardai on at least three occasions from 11.30pm onwards on Christmas night after a large and rowdy crowd of young people began gathering on the street.

One local man said he was told each time gardai were 'monitoring' the situation. He said at no time did he see any gardai as what began as an impromptu street party turned into drunken violence. A car and two motorcycles were brought to the scene by youths and set on fire.

The trouble took place in what remains of the north inner city community virtually in the shadow of major developments associated with Celtic Tiger, including the Financial Services Centre and the National Convention Centre.

Gerry Fay of the North Wall Community Association said: "There's a belief here that this community is being deliberately squeezed out of existence. Of course you have disaffected youths with no prospects of jobs or finding homes to live in near where they grew up.

"I know most of the young people who were out on the street last night and they are mostly good youngsters. It's just there is nothing for them to do and they are denied prospects.

"There's a policy of exclusion going on here that's identical to the 'managed decline' policy that was used under the Tories and Maggie Thatcher to gut the traditional working-class communities in London's docklands. It's exactly the same here," he added.

Mr Fay said promises by successive governments to provide social accommodation in the blocks of apartments built in the Dockland area had been broken.

A spokeswoman for the Garda Ombudsman said: "A motorbike and a Garda patrol car collided, resulting in serious damage to both vehicles and what appears to be serious injury to the driver of the motorbike - a man in his early 20s.

"A team of GSOC investigators has attended the scene and an investigation to establish the circumstances of the collision is being undertaken."

GSOC is appealing for any witnesses to the collision to contact them on 1890 600 800.